Titanium forms thereon an oxidized film and therefore is not easily corroded as compared with general metals, so that it is widely used in a place requiring corrosion resistance. However, in this intended use, there is a demand for titanium having more excellent corrosion resistance, and in order to deal with it, corrosion resistance is improved hitherto by adding another element to titanium.
For example, as titanium having improved corrosion resistance, Ti—Pd alloys, which are also prescribed in JIS 11 type, 12 type and 13 type, are known. These are alloys containing 0.12-0.25% by mass of Pd in pure titanium. Also, it is conventional to contain therein Co, Ni or the like other than Pd (cf. Patent Documents 1 and 2).
Meanwhile, titanium has excellent characteristics as compared with general metals, and specifically it has not only excellent corrosion resistance but also a light weight and a high strength, and therefore various alloys are used in various applications, such as sports goods such as golf clubs and bicycles. However, titanium alloys are expensive compared with general metals, and in these days, utilization of low cost, recycled titanium alloys, which are obtained by recycling not only sponge titanium produced from titanium ores, but also titanium alloys, which were once introduced into markets and had become out of use, are now being studied.
However, when even a small amount of another element is mixed in titanium for which corrosion resistance is required as mentioned above, corrosion may occur starting at such an element, and therefore recycled titanium alloys are not used for titanium alloys for corrosion-resistant materials. Furthermore, platinum group elements, such as Pd, are generally expensive compared with titanium and therefore titanium alloys for corrosion-resistant materials have been very expensive in the past.
In other words, conventional titanium alloys for corrosion-resistant materials have a problem in that they cannot be produced at low cost while maintaining the capability to suppress the deterioration of corrosion resistance.    Patent Document 1: Japanese Patent No. 2132925    Patent Document 2: Japanese Patent Application Publication No. Hei-4-57735